(function (designWidth, maxWidth) {
  var doc = document,
    win = window
  var docEl = doc.documentElement
  var tid
  var rootItem, rootStyle

  function refreshRem () {
    var width = docEl.getBoundingClientRect().width
    var os = function () {
      var ua = navigator.userAgent,
        isWindowsPhone = /(?:Windows Phone)/.test(ua),
        isSymbian = /(?:SymbianOS)/.test(ua) || isWindowsPhone,
        isAndroid = /(?:Android)/.test(ua),
        isFireFox = /(?:Firefox)/.test(ua),
        isTablet = /(?:iPad|PlayBook)/.test(ua) || (isAndroid && !/(?:Mobile)/.test(ua)) || (isFireFox && /(?:Tablet)/.test(ua)),
        isPhone = /(?:iPhone)/.test(ua) && !isTablet,
        isPc = !isPhone && !isAndroid && !isSymbian;
      return {
        isTablet: isTablet,
        isPhone: isPhone,
        isAndroid: isAndroid,
        isPc: isPc
      };
    }();
    // if (os.isAndroid || os.isPhone) {
    //
    // } else
    if (os.isTablet) {
      // console.log("平板")
      width=500

    } else if (os.isPc) {
      // console.log("电脑")
      designWidth = 1600;
      maxWidth = 1700;
    }
    if (!maxWidth) {
      maxWidth = 540
    }
    if (width > maxWidth) {
      width = maxWidth
    }

    // 与淘宝做法不同，直接采用简单的rem换算方法1rem=50px
    var rem = Math.max(width / 7.5, 12); // 10px=0.1rem 且最小12px
    // 兼容UC开始
    rootStyle = 'html{font-size:' + rem + 'px !important}'
    rootItem = document.getElementById('rootsize') || document.createElement('style')
    if (!document.getElementById('rootsize')) {
      document.getElementsByTagName('head')[0].appendChild(rootItem)
      rootItem.id = 'rootsize'
    }
    if (rootItem.styleSheet) {
      rootItem.styleSheet.disabled || (rootItem.styleSheet.cssText = rootStyle)
    } else {
      try { rootItem.innerHTML = rootStyle } catch (f) { rootItem.innerText = rootStyle }
    }
    // 兼容UC结束
    docEl.style.fontSize = rem + 'px'
  };
  refreshRem()

  win.addEventListener('resize', function () {
    clearTimeout(tid) // 防止执行两次
    tid = setTimeout(refreshRem, 300)
  }, false)

  win.addEventListener('pageshow', function (e) {
    if (e.persisted) { // 浏览器后退的时候重新计算
      clearTimeout(tid)
      tid = setTimeout(refreshRem, 300)
    }
  }, false)

  if (doc.readyState === 'complete') {
    doc.body.style.fontSize = '16px'
  } else {
    doc.addEventListener('DOMContentLoaded', function (e) {
      doc.body.style.fontSize = '16px'
    }, false)
  }
})(750, 1334)
